Lifting jack



Marh 6, 1928. 1,661,705 v T. c. PQMEROY LIFTING JACK 77. Filed May 19. 1% 3 Sheets-Sheet 3 4| 35 33 39 5 67 62 45 Patented Mar. 6, 1928.

UNITED STATES PATENT OFFICE.

TIMOTHY C. POMEROY, F MINNEAPOLIS, MINNESOTA.

LISTING JACK.

Application filed May 19, 1926. Serial No. 110,177.

This invention relates to new and useful improvements in hydraulic lifting acks, and more particularly to the form shown in my prior pending application, Serial No. 59,909,.

when being returned to the plunger, as when lowering the jack.

A further and important feature of the invention is to provide such a valve mechanism comprising a pair of check valves and hav 9 ing means mounted in the lifting head thereof adapted to be actuated by rotating the tapered plug securing the. pump to the lifting head, to laterally pry or roll the check valves off their seats, to allow the fluid 5 to return to the plunger, when lowering the liftin head.

A'Eurther and more specific object of the invention is to provide such a valve mechanism comprising a pair of ,ball check valves adapted to control the return flow of the fluid to the plunger, and wedge-shaped thrust members mounted in the head and adapted to engage the valves below their centers whereby, when actuated, the valves will be laterally dislodged from their seats, thereby providing a valve mechanism which may readily be moved into open position without unnecessary strains.

A particular object of the invention, therefore, is to provide an improved valve mechanism for a hydraulic jack, adapted to be actuated by rotation ofthe pivotal connection of the pump with the lifting head thereof, the means engaging the check valves to move them into open position being so disposed as to laterally move the valves from their seats, thereby relieving the pivotal connection between pump and lifting head of unnecessary strains.

Other objects of the invention will appear from the following description and accompanying drawings and will be pointed out in the annexed claims.

In the drawings there has been disclosed a structure designed to carry out the various objects of the invention, but itis to be understood that the invention is not confined to the exact features shown, as various changes may be made within the scope of the claims which follow. I

In the accompanying drawings forming part of this specification:

Figure l is a vertical sectional view of a hydraulic jack showing the improved valve mechanism provided in the lifting head thereof;

Figure 2 is a sectional plan view on the line 22 of Figure 1;

Figure 3 is a detailed sectional view of the lifting head showing the parts in the posiated to raise the plunger;

Fi ure 4 is a similar view showing the position of-the parts when the tapered plug is rotated to unseat the valves;

Figure 5 is a detailed sectional view on the line 55 of Figure 2 showing the notch provided in the tapered plug adapted to be moved into registration with the vent duct to provide a breather for the jack; and

Figure 6 is a sectional view of the tapered plug removed from the lifting head and intermediate handle section.

In the selected embodiment of the invention here shown, for purposes of disclosure, there is illustrated a hydraulic jack similar to the one shown in the above mentioned pending application. This jack comprises a tion assumed when the pump is being opercylinder mounted in a base 12 and having a disc-like plate 13 tightly fitted into the lower end thereof to prevent the walls thereof from collapsing when the jack is operating under a heavy load. A hollow plunger 14 is movably mounted within the cylinder 11. This plunger has a flanged cap 15 mounted in the lower end thereof against which a cupshaped packing 16 is seated. A lifting head 17 is mounted upon the upper end of the plunger 14 and has intake and discharge tubesl8 and 19 secured thereto, and extending downwardly through the plunger as shown in Figure 1. The lower ends of the tubes 18 and 19 pass through alined apertures in the cap 15, gasket 16 and through .a clamping plate 21. A cap 22 is terminally mounted upon the lowerend of the intake tube 18, and an open nut 23 is similarly mounted upon the lower end of the discharge tube 19. By means of the cap 22 and the nut 23 allof the above described parts maybe securely clamped together for operation as a unit.

A feature of the invention resides in the means provided at the upper end of the c linder 11 to prevent leakage of the oil or uid from the cylinder around the plunger.

' by means of a cap 27 mounted in threaded engagement with the cylinder as shown. The cap 27 is provided with an inwardly extending flan e 28 bored to receive the plunger 14 andl iaving its lower face beveled, so that when screwed downwardly on the cylinder, the packing 26 will be firmly pressed against the walls of the plunger to prevent leakage theretnrough.

The plunger 14 is relatively smaller in diameter than the inside bore of the cylinder 11 so as to provide a relatively wide space or gap 29 surrounding the plunger. The cap 15 is provided with an annular outwardly extendin flange 31 which cooperates with the lower ace of the gland 25 to pro-- vide a limit stop for the upward movementof the plunger 14, when the jack is being operated to lift a load and the plunger is raised to the limit of its upward movement. The annular space29 around the plunger also functions as an auxiliary fluid reservoir, it being connected with the interior of the plunger 11 by means of one or more ducts.

32 provided in the lower portion of the plunger 14.

A valve mechanism is provided in the lifting head 17 of the jack to control the flow of the fluid therethrough during the operation of the jack. This' mechanism consists of a pair of ball chec.. valves 33 and 34 mounted in valve chambers 35 and 36, respectively. The valve chamber 35 communicates with the discharge tube 19 through a duct 37, and a relatively shorter duct 38 connects the chamber 36 with the intake tube 18. The valve 33 is normally held against its seat 39 by means of a compression spring 41, while the valve 34 is normally held in its seat 42 by its own weight.

The handle of the jack comprises an intermediate section 42 having one end secured to a threaded socket 43, preferably integrally formed with one end of a tapered plug 4-1 seated in a correspondingly tapered bore 45 provided in the lifting head 17 as shown in igure 2. The opposite end of the plug 44 has formed thereon a reduced cylindrical portion 46, preferably axially alined with the plug and having a washer or disc 47 mounted thereon adapted to engage the face 48. of the hub 49 of the lifting head, in which the tapered bore 45 is provided. A cap 51 Y tapered bore 45 with suflicient pressure to prevent leakage between plug and bore. The plug also provides a pivotal connection between pump handle and lifting head. The operating handle of the jack also comprises a pump section 54 having a pivotal connection with the intermediate section 42 by means of a tapered joint 55, partially shown in Figure 1. A pump rod 56 is reciprocally mounted within the pump section 54 and is operable by means of a hand grip 57 provided thereon as shown. A suitable stufling box 58 is provided upon the upper end of the pump section 54 to prevent oil leakage around the pump rod 56.

Another important feature of the invention resides in the means provided for unseating the valves 33 and 34, when it is desired to permit the oil to return from the cylinder to the interior of the plunger during the operation of lowering the plunger. Such means preferably consists of a pair of thrust members 59 and 61 mounted in the lifting head 17 and adapted to engage, respectively, the check ball valves 33 and 34, as will subsequently be described. The thrust member 59 preferably has a head 62 provided upon one end thereof adapted normally to project into the tapered bore 45 of the lifting head as shown in Figure 1. This head has a series of notches or grooves 60.provided in the periphery thereof to provide a passage for the fluid when the jack is being raised, and as will be subsequently described. The tapered plug 44 has an annular groove 63 provided thereon intermediate its ends, and in this groove a cam 64 is mounted as shown in the drawings. The thrust member 61 is similarly provided with an enlarged head 65 also projecting into the bore 45 and groove 63 as shown. Thus when the plug 44 is rotated, the cam 64 will be moved into en agement with the heads 62 and 65 of the t rust members 59 and 61, respectively, to longitudinally move them in their bearings. Such .movement of the thrust members 59 and 61 will cause the opposite end portions thereof to engage the valves 33 and 34 and laterally move them off their seats. The thrust member 59 is mounted in a bore 66 and has a compression sprin 67 coiled thereabout having one end seate against the head 62, and its other end against the bottom of the bore 66, thereby normally holding themember in the position shown in Figures lafrid 3. The member i 61 is likewise held in the position shown in the center thereof. This member 59 is also provided with a wedge-shaped end portion 69 which, when moved into engagement with the ball 33, will cause the latter to be laterally m ved or rolled oflt' its seat into the position shown in Figure 4. B thus laterally prying or, rolling the bal 33 off its seat, the force required to unseat it will be greatly 1 minimized, thereby relieving the tapered plug 44 of unnecessary strains each time the valve 33 is opened. It has been found in actual practice that by thus prying orirolling the valve 33 from its seat, the pressure in the valve chamber back of the ball will offer very little resistance to the unseating of the ball when the wedgeshaped end portion 69 is moved into engagement with the ball.

The thrust member 61 is likewise provided with a wedge-shaped end portion 71 adapted to be moved into engagement with the ball 34 to 0 en the latter. This wedgeshaped termina 71 of the thrust member 61 is similarly disposed so asto engage the ball 34 below its center, thereby unseating the ball in a manner similar to that described with reference to the ball valve 33 (see Figure 4); The tapered plug 44 has a duct 72 axially provided therein having one end communicating with the threaded socket 43 and its other end communicating with a radial duct 73 connecting it with the annular groove 63 in the plug.

The jack is also provided with a breather or vent whereby it may readily be operated without any tendency of creating a vacuunr within the plunger or cylinder. Such means preferably consists of an air duct 74 provided in the lifting head 17 and connecting the interior of the plunger 11 with the tapered bore 45 in the hub 49 of the lifting head. The upper end of the air duct 74 terminates adjacent the reduced end of the bore 45 as particularly shown in Figure 2. A portion of the reduced end of the tapered plug 44 is cut away to provide a notch 75 as shown in Figures 2 and 5.-

face 48 of the hub 49, thereby allowing the.

air to escape therebetween, when the jack is being 0 erated. Thus when the notch 7 5 is in the ull line position shownin Figure 5 or in the dotted line position shown at A in the same figure, theiinterior of the upper end of the plunger will be in communication with the atmosphere through the duct 74, notch 75, through the central aperture provided in the disc 47, and through jack is in folded position and stored away in the tool box or other storage space.

Figures 3 and 4 illustrate the difi'erent positions of the intermediate handle section 42 of the jack during the raising and lowering operations of the plunger. When the handle is in the position shown in Figure 3, the valves 33 and 34 will be in closed position, and as the pump rod 56 is drawn outwardly or pulled from the pump section 54, the fluid will 'be drawn from the plunger 11 into the intake'tube 18, through the port 76 provided in the lower portion thereof, and upwardly into the valve chamber 36, the valve 34 being unseated by the suction of oil through the port 38. From the valve" chamber 36 the oil will be drawn into the annular grooves 63 in. the plug, thence into the ducts 73' and 72, into the handle section 42, and into the pump section 54. When the pump rod 56 is forced into the handle section 54, the valve 34 will be seated and the pressure of the oil built up in the bore 66 and the-duct 77 connecting it with the valve seat 39, will unseat the check valve 33 to permit the oil to enter the valve chamber 35, after which it will be forced downwardly through the duct 37, tube 19 and into the lower portion of the cylinder beneath the packing 16,secured to the lower end of the plunger, thereby causing the plunger to rise in the cylinder. lVhen the plunger has been moved to the required height and it is desired to release the oil from the cylinder to permit it to return to the plunger, the handle section 42 will be lowered from the position shownin. Figure 3 to that shown in Figure 4. therebyv causing the cam 64 first, to engage the thrust member 62 with the resultant. unseating of the check valve 34, after which it will engage-the head 62 of the thrust member 59 and cause it to be moved into engagement with the check valve 33 with the resultant opening of the latter.

When the valves 33 and 34 have thus been opened, the return flow of the fluid to the plunger will be from the pi e 19, through the duct 37, valve 33, port 72, valve chamber 36, valve 34, port 38, pipe 18 and through the port 80 at the lower end of the pipe 18 and into the plun er. As a result of the terminal (S9 of the t rust member 59 engaging the check valve 33 below its center, as shown in Figures 1 and 3, the ball will be laterally pried or rolled off its seat, such unseating of the valve being accomplished with. very little pressure being exerted against the ball as a result of the terminal 69 engaging the ball below its center as hereinbefore described.

Thus it will readily be noted that by unseating the valve as. above described, the tapered plug 44 will not be subjected to unnecessary side strains such as result when unseating the valves directly against the pressure back of the valves, and as set forth in my prior pending application hereinbefore mentioned. It will also be noted that the valve 34 will be 0 ened while the valve chamber 36 is free 0 any pressure, as the valve 33 alone prevents the return of the fluid from the cylinder to the plunger.

In. the construction of this novel jack, no additional ducts or ports are required to permit the fluid to return from the cylinder to the interior of the plunger, when lowering. the lifting head, which is common practice in jacks of this type. The same ducts are used when raising and lowerin the lifting head, but when the jack is fling lowered, the fluid does not flow through the ports in the tapered plug valve 44, but will follow the course indicated by the arrows; in Figure 4. The return passage of the fluid therefore is very short and direct, resulting in a comparatively quicker release of the fluid.

I claim as my invention:

1. A hydraulic jack comprising in combination, a cylinder, a hollow plunger movable therein, a liftin head on the plunger, a plug valve in sai lifting head having a pump means connected therewith, fluid passages in the head, one communicating with the cylinder and the other with the lunger, check valves in said passages, an means operable by said plug valve to openv and retain said check valves in open osition to permit the return of the fluid to t e plunger without passin through said" plug valve.

2. A hydraulic jack comprising in combination, a cylinder, a hollow plu r, a lifting head on the plunger, a plug va ve in said 11ft head having a pump connected therewith or transferring the fluid from the plunger to the cylinder to raise the plunger,- fluid passages in the head one communicatin with the cylinder and the other w th the iunger and both communicating with 'bers to cause the latter to open an said plug valve, check valves in said passages, and means operable by rotation of said plug valve to successively open and retain said check valves in open position to permit the return of the fluid to the plunger without passing through said plug valve.

3. A hydraulic jack comprising in combination, a cylinder, a hollow plunger 0. liftin head on the plunger, a plug valve in said li tin head havin a pump operatively connecte therewith or pumping the fluid into the cylinder to raise the plunger, fluid passages in the head, one communicatin with the cylinder and the other with the plunger and th communicating with said plu valve, check valves in said passages, an spring'actuated thrust members mounted in said passages and adapted to en age and open said check valves to permit t e return of the fluid to the plunger without passing through said plug valve, said thrust members being operable by means on said'plug valve.

4. A hydraulic jack comprising in combination, a cylinder, a hollow plunger, a lifting head on the plunger, a plug valve in said lifting head having a pump operatively connected therewith for pumping the fluid into the cylinder beneath the plunger, fluid passages in the head, one communicating with the cylinder and the other with the plunger and both communicating withv said plug valve, check valves in said passages, springactuated valve-unseating members mounted in said passages and normally out of engagement with said valves, and a cam on said plug valve adapted to engage and actuate said members to open said valves to permit the return of the fluid to the plunger without passing" through the lug valve. 5. A hydraulic jac comprising in combination, a cylinder, a hollow plun er, a lifting head on jhe plunger, a plug va ve in said liftin head iaving a pump operatively connecte therewith for pumping the fluid into and both communicating with said p ug valve, check valves in said passages, an annular groove in the periphery of the plug valve for establishing communication between said fluid passages and the pump, a valve-opening member ineach passage havannular adapted to engage said valve-openin memretain said check valves in 0 en position to permit the return of the flui from the cylinder to the plunger.

In witness whereof, I have hereunto set my hand this 7th day of May, 1926.

TIMOTHY o. PoMERoY.

ing one end normally extending into said groove, and a cam in said groove 

